*
*/
-#include "brw_cfg.h"
+#include "brw_vec4.h"
#include "brw_vec4_live_variables.h"
using namespace brw;
+#define MAX_INSTRUCTION (1 << 30)
+
/** @file brw_vec4_live_variables.cpp
*
* Support for computing at the basic block level which variables
*/
/**
- * Sets up the use[] and def[] arrays.
+ * Sets up the use/def arrays and block-local approximation of the live ranges.
*
* The basic-block-level live variable analysis needs to know which
* variables get used before they're completely defined, and which
assert(cfg->blocks[block->num - 1]->end_ip == ip - 1);
foreach_inst_in_block(vec4_instruction, inst, block) {
- struct vec4_block_data *bd = &block_data[block->num];
+ struct block_data *bd = &block_data[block->num];
- /* Set use[] for this instruction */
+ /* Set up the instruction uses. */
for (unsigned int i = 0; i < 3; i++) {
if (inst->src[i].file == VGRF) {
for (unsigned j = 0; j < DIV_ROUND_UP(inst->size_read(i), 16); j++) {
for (int c = 0; c < 4; c++) {
const unsigned v = var_from_reg(alloc, inst->src[i], c, j);
+
+ start[v] = MIN2(start[v], ip);
+ end[v] = ip;
+
if (!BITSET_TEST(bd->def, v))
BITSET_SET(bd->use, v);
}
}
}
- /* Check for unconditional writes to whole registers. These
- * are the things that screen off preceding definitions of a
- * variable, and thus qualify for being in def[].
- */
- if (inst->dst.file == VGRF &&
- (!inst->predicate || inst->opcode == BRW_OPCODE_SEL)) {
+ /* Set up the instruction defs. */
+ if (inst->dst.file == VGRF) {
for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
for (int c = 0; c < 4; c++) {
if (inst->dst.writemask & (1 << c)) {
const unsigned v = var_from_reg(alloc, inst->dst, c, i);
- if (!BITSET_TEST(bd->use, v))
+
+ start[v] = MIN2(start[v], ip);
+ end[v] = ip;
+
+ /* Check for unconditional register writes, these are the
+ * things that screen off preceding definitions of a
+ * variable, and thus qualify for being in def[].
+ */
+ if ((!inst->predicate || inst->opcode == BRW_OPCODE_SEL) &&
+ !BITSET_TEST(bd->use, v))
BITSET_SET(bd->def, v);
}
}
cont = false;
foreach_block_reverse (block, cfg) {
- struct vec4_block_data *bd = &block_data[block->num];
+ struct block_data *bd = &block_data[block->num];
/* Update liveout */
foreach_list_typed(bblock_link, child_link, link, &block->children) {
- struct vec4_block_data *child_bd = &block_data[child_link->block->num];
+ struct block_data *child_bd = &block_data[child_link->block->num];
for (int i = 0; i < bitset_words; i++) {
BITSET_WORD new_liveout = (child_bd->livein[i] &
}
}
-vec4_live_variables::vec4_live_variables(const simple_allocator &alloc,
- cfg_t *cfg)
- : alloc(alloc), cfg(cfg)
+/**
+ * Extend the start/end ranges for each variable to account for the
+ * new information calculated from control flow.
+ */
+void
+vec4_live_variables::compute_start_end()
+{
+ foreach_block (block, cfg) {
+ const struct block_data &bd = block_data[block->num];
+
+ for (int i = 0; i < num_vars; i++) {
+ if (BITSET_TEST(bd.livein, i)) {
+ start[i] = MIN2(start[i], block->start_ip);
+ end[i] = MAX2(end[i], block->start_ip);
+ }
+
+ if (BITSET_TEST(bd.liveout, i)) {
+ start[i] = MIN2(start[i], block->end_ip);
+ end[i] = MAX2(end[i], block->end_ip);
+ }
+ }
+ }
+}
+
+vec4_live_variables::vec4_live_variables(const backend_shader *s)
+ : alloc(s->alloc), cfg(s->cfg)
{
mem_ctx = ralloc_context(NULL);
num_vars = alloc.total_size * 8;
- block_data = rzalloc_array(mem_ctx, struct vec4_block_data, cfg->num_blocks);
+ start = ralloc_array(mem_ctx, int, num_vars);
+ end = ralloc_array(mem_ctx, int, num_vars);
+
+ for (int i = 0; i < num_vars; i++) {
+ start[i] = MAX_INSTRUCTION;
+ end[i] = -1;
+ }
+
+ block_data = rzalloc_array(mem_ctx, struct block_data, cfg->num_blocks);
bitset_words = BITSET_WORDS(num_vars);
for (int i = 0; i < cfg->num_blocks; i++) {
setup_def_use();
compute_live_variables();
+ compute_start_end();
}
vec4_live_variables::~vec4_live_variables()
ralloc_free(mem_ctx);
}
-#define MAX_INSTRUCTION (1 << 30)
-
-/**
- * Computes a conservative start/end of the live intervals for each virtual GRF.
- *
- * We could expose per-channel live intervals to the consumer based on the
- * information we computed in vec4_live_variables, except that our only
- * current user is virtual_grf_interferes(). So we instead union the
- * per-channel ranges into a per-vgrf range for virtual_grf_start[] and
- * virtual_grf_end[].
- *
- * We could potentially have virtual_grf_interferes() do the test per-channel,
- * which would let some interesting register allocation occur (particularly on
- * code-generated GLSL sequences from the Cg compiler which does register
- * allocation at the GLSL level and thus reuses components of the variable
- * with distinct lifetimes). But right now the complexity of doing so doesn't
- * seem worth it, since having virtual_grf_interferes() be cheap is important
- * for register allocation performance.
- */
-void
-vec4_visitor::calculate_live_intervals()
+static bool
+check_register_live_range(const vec4_live_variables *live, int ip,
+ unsigned var, unsigned n)
{
- if (this->live_intervals)
- return;
-
- int *start = ralloc_array(mem_ctx, int, this->alloc.total_size * 8);
- int *end = ralloc_array(mem_ctx, int, this->alloc.total_size * 8);
- ralloc_free(this->virtual_grf_start);
- ralloc_free(this->virtual_grf_end);
- this->virtual_grf_start = start;
- this->virtual_grf_end = end;
-
- for (unsigned i = 0; i < this->alloc.total_size * 8; i++) {
- start[i] = MAX_INSTRUCTION;
- end[i] = -1;
+ for (unsigned j = 0; j < n; j += 4) {
+ if (var + j >= unsigned(live->num_vars) ||
+ live->start[var + j] > ip || live->end[var + j] < ip)
+ return false;
}
- /* Start by setting up the intervals with no knowledge of control
- * flow.
- */
- int ip = 0;
- foreach_block_and_inst(block, vec4_instruction, inst, cfg) {
- for (unsigned int i = 0; i < 3; i++) {
- if (inst->src[i].file == VGRF) {
- for (unsigned j = 0; j < DIV_ROUND_UP(inst->size_read(i), 16); j++) {
- for (int c = 0; c < 4; c++) {
- const unsigned v = var_from_reg(alloc, inst->src[i], c, j);
- start[v] = MIN2(start[v], ip);
- end[v] = ip;
- }
- }
- }
- }
+ return true;
+}
- if (inst->dst.file == VGRF) {
- for (unsigned i = 0; i < DIV_ROUND_UP(inst->size_written, 16); i++) {
- for (int c = 0; c < 4; c++) {
- if (inst->dst.writemask & (1 << c)) {
- const unsigned v = var_from_reg(alloc, inst->dst, c, i);
- start[v] = MIN2(start[v], ip);
- end[v] = ip;
- }
+bool
+vec4_live_variables::validate(const backend_shader *s) const
+{
+ unsigned ip = 0;
+
+ foreach_block_and_inst(block, vec4_instruction, inst, s->cfg) {
+ for (unsigned c = 0; c < 4; c++) {
+ if (inst->dst.writemask & (1 << c)) {
+ for (unsigned i = 0; i < 3; i++) {
+ if (inst->src[i].file == VGRF &&
+ !check_register_live_range(this, ip,
+ var_from_reg(alloc, inst->src[i], c),
+ regs_read(inst, i)))
+ return false;
}
+
+ if (inst->dst.file == VGRF &&
+ !check_register_live_range(this, ip,
+ var_from_reg(alloc, inst->dst, c),
+ regs_written(inst)))
+ return false;
}
}
ip++;
}
- /* Now, extend those intervals using our analysis of control flow.
- *
- * The control flow-aware analysis was done at a channel level, while at
- * this point we're distilling it down to vgrfs.
- */
- this->live_intervals = new(mem_ctx) vec4_live_variables(alloc, cfg);
-
- foreach_block (block, cfg) {
- struct vec4_block_data *bd = &live_intervals->block_data[block->num];
-
- for (int i = 0; i < live_intervals->num_vars; i++) {
- if (BITSET_TEST(bd->livein, i)) {
- start[i] = MIN2(start[i], block->start_ip);
- end[i] = MAX2(end[i], block->start_ip);
- }
-
- if (BITSET_TEST(bd->liveout, i)) {
- start[i] = MIN2(start[i], block->end_ip);
- end[i] = MAX2(end[i], block->end_ip);
- }
- }
- }
-}
-
-void
-vec4_visitor::invalidate_live_intervals()
-{
- ralloc_free(live_intervals);
- live_intervals = NULL;
+ return true;
}
int
-vec4_visitor::var_range_start(unsigned v, unsigned n) const
+vec4_live_variables::var_range_start(unsigned v, unsigned n) const
{
- int start = INT_MAX;
+ int ip = INT_MAX;
for (unsigned i = 0; i < n; i++)
- start = MIN2(start, virtual_grf_start[v + i]);
+ ip = MIN2(ip, start[v + i]);
- return start;
+ return ip;
}
int
-vec4_visitor::var_range_end(unsigned v, unsigned n) const
+vec4_live_variables::var_range_end(unsigned v, unsigned n) const
{
- int end = INT_MIN;
+ int ip = INT_MIN;
for (unsigned i = 0; i < n; i++)
- end = MAX2(end, virtual_grf_end[v + i]);
+ ip = MAX2(ip, end[v + i]);
- return end;
+ return ip;
}
bool
-vec4_visitor::virtual_grf_interferes(int a, int b)
+vec4_live_variables::vgrfs_interfere(int a, int b) const
{
return !((var_range_end(8 * alloc.offsets[a], 8 * alloc.sizes[a]) <=
var_range_start(8 * alloc.offsets[b], 8 * alloc.sizes[b])) ||
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